CN105629495A - Radial polarization beam generation device on the basis of radial polarization splitting prism - Google Patents

Abstract

The present invention provides a radial polarization beam generation device on the basis of a radial polarization splitting prism. The radial polarization beam generation device comprises: a laser light source, a quarter-wave plate, laser beam expanders, a spiral phase plate, a radial polarization splitting prism, a polarizing film, a lens and a CCD camera. The laser light source emits a horizontal polarized light and is converted to a circular polarization light beam after passing through the quarter-wave plate horizontally arranged at a fast axis direction; the circular polarization light beam is vertically incident into the center of the spiral phase plate after being expanded and collimated through the laser beam expanders, a spiral light beam is emitted and vertically incident into the center of the radial polarization splitting prism, and the outgoing beam is the radial polarization beam; and the polarizing film for detection of the radial polarization beam is disposed between the radial polarization splitting prism and the lens, and the CCD camera is configured to detection of light distribution after the radial polarization beam passes through the lens.

Description

Based on the radial polarized light beam generating apparatus of radial polarisation beam splitting prism

Technical field

The present invention relates to field of photoelectric technology, in particular to the device of a kind of generation radial polarized light beam based on radial polarisation beam splitting prism.

Background technology

Because radial polarized light beam has the polarization structure of rotational symmetry and the intensity distribution of hollow, so that it shows unique advantage in some scientific researches and field of engineering technology. Particularly radial polarized light beam, owing to it is under high numerical aperture lens focuses on, focal beam spot can break through diffraction limit, and has very strong longitudinal electric field component near focus. The R.Dorn etc. of Germany in 2003 reports their experimental result on PhysicsReviewLetters, can obtain being less than the focal beam spot (being less than limit focal beam spot 0.26 �� 2 of linear polarization light beam) of 0.16 �� 2 for radial polarisation light. At present, radial polarized light beam is reported in a large number in the application in the fields such as charged corpuscle acceleration, particle-capture, biomedicine, high-resolution imaging technology and laser processing.

At present, the generation method of radial polarized light beam is still domestic and international research focus. The method producing radial polarized light beam can be divided into two classes: the outer conversion method in method and chamber in chamber, and the former is similar to the laser apparatus making a generation radial polarized light beam; The light beam of laser apparatus outgoing is carried out conversion to produce radial polarized light beam by the latter. Outside the main chamber adopted, method for transformation has the method such as optics coherence tomography technology, space polarization device at present. Common space polarization device has combination half-wave plate, sub-wave length grating and liquid crystal polarized conversion devices. Above-mentioned space polarization device is discontinuous device, and advantage easy to process can generate high-order radial polarized light beam flexibly, and shortcoming is that transformation efficiency is not high and to generate the purity of radial polarized light beam not high.

The radial polarized light beam generating apparatus of purity and transformation efficiency can be improved consequently, it is desirable to a kind of.

Summary of the invention

It is an object of the invention to provide the device of a kind of generation radial polarized light beam based on radial polarisation beam splitting prism, comprising: LASER Light Source, quarter-wave plate, laser beam expanding lens, helical phase sheet, radial polarisation beam splitting prism, polaroid, lens and CCD camera; From the horizontal polarized light of LASER Light Source outgoing, circularly polarized light beam is changed into after the quarter-wave plate of too fast axle horizontal positioned, described circularly polarized light beam impinges perpendicularly on the center of described helical phase sheet after laser beam expanding lens beam-expanding collimation, outgoing spiral light beam, impinging perpendicularly on the center of described radial polarisation beam splitting prism, outgoing beam is radial polarized light beam; One is placed for detecting the described polaroid of radial polarized light beam, by carrying out the detection of light distribution after described lens by described CCD camera between described radial polarisation beam splitting prism and lens.

Preferably, described radial polarisation beam splitting prism comprises a plano-convex axial cone mirror and a flat recessed axial cone mirror.

Preferably, the recessed axial cone mirror of described plano-convex axial cone mirror peace to be two drift angles the be complementary axial cone mirror of 90 ��.

Preferably, the conical surface of described plano-convex axial cone mirror is coated with polarization beam splitter.

Preferably, the material of the recessed axial cone mirror of described plano-convex axial cone mirror peace is fused quartz K9 or ZF glass.

Preferably, described radial polarized light beam can represent and is:

$J\left(\mathrm{\φ}\right)=\left[\begin{array}{c}cos\mathrm{\φ}\\ sin\mathrm{\φ}\end{array}\right]$

Wherein �� is position angle.

Preferably, described radial polarisation beam splitting prism can be expressed as Jones Matrix formalism:

$M\left(\mathrm{\φ}\right)=\left[\begin{array}{cc}{\cos }^2\mathrm{\φ}& sin\mathrm{\φ}cos\mathrm{\φ}\\ \sin \mathrm{\φ}\cos \mathrm{\φ}& {\sin }^2\mathrm{\φ}\end{array}\right]$

It is to be understood that describing of aforementioned cardinal principle is exemplary illustration and explanation with follow-up detailed description, the restriction to the claimed content of the present invention should not be used as.

Accompanying drawing explanation

With reference to the accompanying drawing enclosed, the more object of the present invention, function and advantage are illustrated by the following description of embodiment of the present invention, wherein:

Fig. 1 schematically shows the structural representation of the device of the generation radial polarized light beam based on radial polarisation beam splitting prism according to the present invention.

Fig. 2 (a) diagrammatically illustrates the vertical profile structural representation of radial polarisation beam splitting prism.

Fig. 2 (b) diagrammatically illustrates the 3-D solid structure schematic diagram of radial polarisation beam splitting prism.

Fig. 3 generates the light distribution of a rank radial polarized light beam and the light distribution schematic diagram after analyzer.

Embodiment

Fig. 1 diagrammatically illustrates the device 100 of the generation radial polarized light beam based on radial polarisation beam splitting prism according to the present invention. as shown in Figure 1, described device 100 comprises: LASER Light Source 101, quarter-wave plate 102, laser beam expanding lens 103, helical phase sheet 104, radial polarisation beam splitting prism 105, polaroid 106, lens 107 and CCD camera 108. after the quarter-wave plate 102 of too fast axle horizontal positioned, circularly polarized light beam is changed into from the horizontal polarized light of LASER Light Source 101 outgoing, circularly polarized light impinges perpendicularly on the center of a rank helical phase sheet 104 after laser beam expanding lens 103 beam-expanding collimation, one rank spiral light beam of outgoing impinges perpendicularly on the center of radial polarisation beam splitting prism 105, outgoing beam is a rank radial polarized light beam, in order to detect radial polarized light beam, a polaroid 106 is placed between radial polarisation beam splitting prism 105 and lens 107, by carrying out the detection of light distribution after lens 107 by CCD camera 108.

Fig. 2 diagrammatically illustrates the structural representation of radial polarisation beam splitting prism 105. Fig. 2 (a) diagrammatically illustrates the vertical profile structural representation of radial polarisation beam splitting prism. Fig. 2 (b) diagrammatically illustrates the 3-D solid structure schematic diagram of radial polarisation beam splitting prism.

As shown in Fig. 2 (a), radial polarisation beam splitting prism 105 is made as matrix by the complementary axial cone mirror (a plano-convex axial cone mirror 1051 and a flat recessed axial cone mirror 1052) that two drift angles are 90 ��, material is fused quartz K9 or ZF glass, and wherein the conical surface of plano-convex axial cone mirror 1051 is coated with polarization beam splitter. By optical cement 1053, the conical surface of two axial cone mirrors being composed a device, the plane of two axial cone mirrors is all coated with anti-reflection film.

Below, Jones's vector Jones's matrix is adopted generative process to be described. A kind of mathematics instrument that Jones's vector Jones's matrix widely uses when being and analyze light beam and polarization optical element, in Jones's vector, the electric field along the light beam of z-axis propagation is decomposed into x-component and y-component, and represents by a column vector. In addition, optical element can represent to be 2 �� 2 matrix axially symmetry polarization distributions

Definition according to vector beam, its polarisation distribution can represent and is:

$\stackrel{\‾}{J}\left(\mathrm{\φ}\right)=\left[\begin{array}{c}cos(m\mathrm{\φ}+{\mathrm{\φ}}_0)\\ \sin (m\mathrm{\φ}+{\mathrm{\φ}}_0)\end{array}\right]---\left(1\right)$

Wherein ��₀Being initial polarization direction, and �� is position angle, m is the rank number of radial polarized light beam, is also referred to as polarization topology lotus. As m=0, above-mentioned Jones's vector no longer represents vector beam, and the angle representing polarization direction and x-axis isLine polarized light, can represent and be:

${\stackrel{\‾}{J}}_{linear}=\left(\begin{array}{c}{\mathrm{cos\φ}}_0\\ {\mathrm{sin\φ}}_0\end{array}\right)---\left(2\right)$

As m=1 andTime, represent radial polarisation light

${\stackrel{\‾}{J}}_{radial}\left(\begin{array}{c}\cos \mathrm{\φ}\\ \sin \mathrm{\φ}\end{array}\right)---\left(3\right)$

As m=1 andTime, represent that angle is to polarized light

Radial polarisation beam splitting prism in Fig. 2 can be expressed as Jones Matrix formalism:

$M\left(\mathrm{\φ}\right)=\left[\begin{array}{cc}{\cos }^2\mathrm{\φ}& sin\mathrm{\φ}\cos \mathrm{\φ}\\ sin\mathrm{\φ}\cos \mathrm{\φ}& {\sin }^2\mathrm{\φ}\end{array}\right]---\left(5\right)$

Therefore, it is possible to after the spiral light beam being-1 with a branch of topology lotus (track azimuthal quantum number) incides radial polarisation beam splitting prism, its transmission light beam is radial polarized light beam. Its generative process can describe by mathematical expression formula below:

$\begin{array}{c}{\stackrel{\→}{E}}_{out}=M\left(\mathrm{\φ}\right)\exp (-i\mathrm{\φ})\frac{1}{\sqrt{2}}\left[\begin{array}{c}1\\ i\end{array}\right]\\ =\left[\begin{array}{c}\cos \mathrm{\φ}\\ \sin \mathrm{\φ}\end{array}\right]\end{array}---\left(6\right)$

Embodiment:

First, making the radial polarisation beam splitting prism of different wave length according to the wavelength of the Output of laser of LASER Light Source and bandwidth, specific embodiments is the polarization beam splitter and the anti-reflection film that plate respective wavelength and bandwidth on the conical surface and plane of axial cone mirror. The Nd:YAG Solid State Laser light source exported for linear polarization below describes the process generating radial polarized light beam with radial polarisation beam splitting prism:

From Nd:YAG Solid State Laser light source export 1064nm horizontal direction linearly polarized laser light source through laser beam expanding lens expand standard after again after the quarter-wave plate and helical phase sheet of quick shaft direction level, outgoing beam is the spiral light beam of dextropolarization, then the center of radial polarisation beam splitting prism is impinged perpendicularly on, through the light beam of radial polarisation beam splitting prism again through lens, outgoing beam is exactly radial polarized light beam, and its light distribution becomes ring-type.

Being radial polarized light beam to detect outgoing beam, can determine with the change of CCD camera and the radial polarisation beam splitting prism observation light distribution of rotation, Fig. 3 generates the light distribution of a rank radial polarized light beam and the light distribution schematic diagram after analyzer. Its rule is, the light intensity pattern through radial polarisation beam splitting prism splits into two lobes, and along with the rotation of radial polarisation beam splitting prism, intensity image rotates thereupon, and the sense of rotation speed of rotation with radial polarisation beam splitting prism is consistent.

By the device of the generation radial polarized light beam based on radial polarisation beam splitting prism of the present invention, wherein have employed one and complementary axial cone mirror is made radial polarisation beam splitting prism, it is designed to successive type space polarization device, with it, spiral light beam of circular polarization is changed into radial polarized light beam, based on the continuity of device, can having very big breakthrough in the purity generating radial polarized light beam and efficiency, particularly purity is very high, can reach 100% in theory. The circular polarization spiral light beam of incidence can be changed into a rank radial polarized light beam of high purity with radial polarisation beam splitting prism, owing to radial polarisation beam splitting prism can be used in very wide laser wavelength, so radial polarisation beam splitting prism is desirable for generating the achromatism space polarization device of wide band radial polarized light beam. It is applicable to femtosecond laser, super continuum source, super-fluorescence light source are changed into radial polarized light beam. In addition, this radial polarisation beam splitting prism can generate the radial polarized light beam of twin nuclei after transformation further, and this type of light beam has important application prospect in light high-resolution imaging field of kneading.

In conjunction with explanation and the practice of the present invention disclosed here, other embodiments of the present invention all are easy to expect for those skilled in the art and understand. Illustrating and be only considered as exemplary with embodiment, true scope and the purport of the present invention are limited by claim.

Claims (7)

1., based on the device of radial polarized light beam for radial polarisation beam splitting prism, comprising:

LASER Light Source, quarter-wave plate, laser beam expanding lens, helical phase sheet, radial polarisation beam splitting prism, polaroid, lens and CCD camera;

From the horizontal polarized light of LASER Light Source outgoing, circularly polarized light beam is changed into after the quarter-wave plate of too fast axle horizontal positioned, described circularly polarized light beam impinges perpendicularly on the center of described helical phase sheet after laser beam expanding lens beam-expanding collimation, outgoing spiral light beam, impinging perpendicularly on the center of described radial polarisation beam splitting prism, outgoing beam is radial polarized light beam;

One is placed for detecting the described polaroid of radial polarized light beam, by carrying out the detection of light distribution after described lens by described CCD camera between described radial polarisation beam splitting prism and lens.

2. device as claimed in claim 1, described radial polarisation beam splitting prism comprises a plano-convex axial cone mirror and a flat recessed axial cone mirror.

3. device as claimed in claim 2, the described plano-convex axial cone mirror recessed axial cone mirror of peace to be two drift angles the be complementary axial cone mirror of 90 ��.

4. device as claimed in claim 2 or claim 3, the conical surface of described plano-convex axial cone mirror is coated with polarization beam splitter.

5. device as claimed in claim 2 or claim 3, the material of the described plano-convex axial cone mirror recessed axial cone mirror of peace is fused quartz K9 or ZF glass.

6. device as claimed in claim 1, described radial polarized light beam can represent and is:

$J\left(\mathrm{\φ}\right)=\left[\begin{array}{c}cos\mathrm{\φ}\\ sin\mathrm{\φ}\end{array}\right]$

Wherein �� is position angle.

7. device as claimed in claim 1, described radial polarisation beam splitting prism can be expressed as Jones Matrix formalism:

$M\left(\mathrm{\φ}\right)=\left[\begin{array}{cc}{\cos }^2\mathrm{\φ}& sin\mathrm{\φ}cos\mathrm{\φ}\\ sin\mathrm{\φ}\cos \mathrm{\φ}& {\sin }^2\mathrm{\φ}\end{array}\right]$